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A030679 Cube root of A030678.

%I A030679 #12 May 18 2019 00:19:36
%S A030679 5,3,7,16,8,4,9,20,21,48,61,15,164,82,188,92,96,215,466,481,23,236,
%T A030679 242,533,253,258,122,576,587,277,606,615,624,632,64,301,656,143,312,
%U A030679 679,1479,322,70,707,714,72,1565,34,1593,346,1619,1632,763,357,1668
%N A030679 Cube root of A030678.
%H A030679 Robert Israel, <a href="/A030679/b030679.txt">Table of n, a(n) for n = 1..10000</a>
%F A030679 a(n) = A030669(A002113(n+1)) = A030678(n)^(1/3). - _Robert Israel_, Dec 25 2018
%p A030679 N:= 3: # to get extensions of all palindromes of <= N digits
%p A030679 f:= proc(n) local d, x;
%p A030679   for d from 1 do
%p A030679     x:= ceil((n*10^d)^(1/3));
%p A030679     if x^3 < (n+1)*10^d then return x fi
%p A030679   od
%p A030679 end proc:
%p A030679 digrev:= proc(n) local i, L;
%p A030679   L:= convert(n, base, 10);
%p A030679   add(L[-i]*10^(i-1), i=1..nops(L))
%p A030679 end proc:
%p A030679 Res:= seq(f(i), i=1..9):
%p A030679 for d from 2 to N do
%p A030679 if d::even then
%p A030679     m:= d/2;
%p A030679     Res:= Res, seq(f(n*10^m + digrev(n)), n=10^(m-1)..10^m-1);
%p A030679 else
%p A030679     m:= (d-1)/2;
%p A030679     Res:= Res, seq(seq(f(n*10^(m+1)+y*10^m+digrev(n)), y=0..9), n=10^(m-1)..10^m-1)
%p A030679 fi
%p A030679 od: Res; # _Robert Israel_, Dec 25 2018
%Y A030679 Cf. A002113, A030669, A030678.
%K A030679 nonn,base
%O A030679 1,1
%A A030679 _Patrick De Geest_